There are SO many jokes that start with "a guy goes to a doctor..." and goes on from there.
The punchlines tend to be about the various maladies or the doctor's response. We don't know if there are any specific jokes about patients not being able to afford treatment, and that might be because that's a real-life situation for many people, and not a funny one.
Michael Stein, himself an MD, realized that's one thing doctors seldom ask about--and should. Because even a dedicated patient determined to get well can't follow advice and prescriptions if they can't afford to.
Patient conversations power Stein's book Broke: Patients Talk about Money with Their Doctor. We go micro and macro in this conversation from 2020.